Compared with the previous version v2, new signal types such as Optical Data Unit (ODU)0, ODU4, ODU2e and flexible rate ODU (ODUflex) are newly added in the version v3 of G.709 of the International Telecommunication Union Telecommunication Standardization Sector (ITU-T). The ODUflex is used to transparently bit-transmit client signals at any rates through Optical Transport Network (OTN) and use a Generic Mapping Procedure (GMP) to map the ODUflex into a High Order ODU (HO ODU). The ODUflex can be adaptive to client signals at any rates, and then a Low Order ODU (LO ODU) is mapped into a corresponding number of tributary timeslots of the HO ODU. In this technology, not only effective transmission of the existing various client signals is considered, but also client signals which will appear in the future in the meantime. The ODUflex is divided into two kinds, one is used for bearing ODUflex(CBR) of Constant Bit Rate (CBR) client signals, and the CBR client signals are mapped into the ODUflex(CBR) through the GMP; and the other one is used for bearing ODUflex(GFP) of packet client signals, and the packet client signals are encapsulated into the ODUflex(GFP) through a Generic Framing Procedure (GFP).
With regard to the ODUflex(GFP), since the bandwidth of the packet client signals will be changed over time, allocating fixed bandwidths to the ODUflex(GFP) will not be beneficial to the effective utilization of bandwidth resources. If the ODUflex(GFP) can support a dynamic bandwidth adjustment, not only various bandwidth requirements of the packet client signals can be better satisfied, but also the bandwidth utilization ratio can be effectively improved and the bandwidth resources can be saved. Therefore, the ODUflex(GFP) is required to have a bandwidth hitless resizing capability. The ODUflex(GFP) bandwidth hitless resizing means that the ODUflex(GFP) is required to complete the bandwidth resizing in the case of dynamic and no interruption of the existing services. However, in the related art, not all interfaces support the ODUflex bandwidth hitless resizing capability, a plurality of interfaces do not support the ODUflex bandwidth hitless resizing capability, when it is required to select links which have the ODUflex bandwidth hitless resizing capability, a control plane is required to be able to discover which links have the ODUflex bandwidth hitless resizing capability and then to flood the information out through a routing protocol.